The first to convert AC voltage into DC voltage; The second one converts this DC voltage into an AC voltage with variable amplitude and frequency.

Therefore, they together form an AC to AC converter tool that can be placed between a regular power grid and loads with special requirements for voltage and frequency characteristics.

The AC voltage becomes positive or negative rectified. In fact, what is being rectified is the current. In order to rectify the voltage, an additional capacitor is required. The second reason for using diodes as the basic components of rectifiers in power inverters is that compared to other semiconductor technologies, the cost of diodes is lower. Diodes are also much more robust

than other (control) semiconductors. The third reason for choosing a diode is that there is no control over electronic devices to make the diode conduct or not conduct. The reversing process occurs naturally, so there is no need for control.